NAME

BIO_s_fd, BIO_set_fd, BIO_get_fd, BIO_new_fd − File descriptor BIO

SYNOPSIS

#include <openssl/bio.h>
BIO_METHOD ∗BIO_s_fd(
        void );

#define BIO_set_fd(b,fd,c)BIO_int_ctrl(b,BIO_C_SET_FD,c,fd)
#define BIO_get_fd(b,c)BIO_ctrl(b,BIO_C_GET_FD,0,(char ∗)c)

BIO ∗BIO_new_fd(
        int fd,
        int close_flag );

DESCRIPTION

The BIO_s_fd() function returns the file descriptor BIO method. This is a wrapper around the platform’s file descriptor routines, such as read() and write(). 

The BIO_read() and BIO_write() functions read or write the underlying descriptor.  BIO_puts() is supported, but BIO_gets() is not. 

If the close flag is set then then close() is called on the underlying file descriptor when the BIO is freed. 

The BIO_reset() function attempts to change the file pointer to the start of file using lseek(fd, 0, 0). 

The BIO_seek() function sets the file pointer to position ofs from start of file using lseek(fd, ofs, 0). 

The BIO_tell() function returns the current file position by calling lseek(fd, 0, 1). 

The BIO_set_fd() function sets the file descriptor of BIO b to fd and the close flag to c. 

The BIO_get_fd() function places the file descriptor in c if it is not NULL. It also returns the file descriptor.  If c is not NULL it should be of type (int ∗). 

The BIO_new_fd() function returns a file descriptor BIO using fd and close_flag. 

NOTES

The behavior of the BIO_read() and BIO_write() functions depends on the behavior of the platform’s read() and write() calls on the descriptor. If the underlying  file descriptor is in a nonblocking mode then the BIO will behave in the manner described in the BIO_read(3) and BIO_should_retry(3) reference pages. 

File descriptor BIOs should not be used for socket I/O. Use socket BIOs instead. 

RETURN VALUES

BIO_s_fd() returns the file descriptor BIO method. 

BIO_reset() returns zero for success and -1 if an error occurred.  BIO_seek() and BIO_tell() return the current file position or -1 is an error occurred. These values reflect the underlying lseek() behavior. 

BIO_set_fd() always returns 1. 

BIO_get_fd() returns the file descriptor or -1 if the BIO has not been initialized. 

BIO_new_fd() returns the newly allocated BIO or NULL is an error occurred. 

EXAMPLES

This is a file descriptor BIO version of "Hello World":

BIO ∗out;
out = BIO_new_fd(fileno(stdout), BIO_NOCLOSE);
BIO_printf(out, "Hello World\n");
BIO_free(out);

SEE ALSO

Functions: BIO_seek(3), BIO_tell(3), BIO_reset(3), BIO_read(3), BIO_write(3), BIO_puts(3), BIO_gets(3), BIO_printf(3), BIO_set_close(3), BIO_get_close(3)